Fix issue in ContentNeogitatingViewResolver

The following commit in 3.2.3 had a side effect on CNVR:
https://github.com/SpringSource/spring-framework/commit/aaded7e30b06cc70a354856a2288acd04045b673

It appears that CNVR doesn't treat a request for "*/*" differently
from a request that does not request content types. Both should be
interpreted as "any content type is acceptable". This fix ensures
that CNVR treats these two cases the same way.

Issue: SPR-10683